Properties of the 47KDa Protein and the D1-D2-Cyt B559 Complex
In the present paper we describe a new method for the isolation of the 47 kDa protein and the D1-D2-Cyt b559 complex that uses the non-ionic detergent dodecylmaltoside in combination with high concentrations of lithium Perchlorate to dissociate polypeptides of the PSII complex, followed by FPLC ion-exchange chromatography to separate these polypeptides. By carrying out a low temperature EPR study of the two systems we support the proposal that the D1-D2 complex, and not the 47 kDa polypeptide, is the species which binds the reaction center öf PSII. The EPR signal from the spin-polarized triplet was also used as a probe of the stability of the D1-D2-Cyt b559 preparation. It was found that more than 80% of the EPR signal intensity from the spin-polarized triplet could still be observed after incubation of our D1-D2-Cyt b559 complex in the dark at room temperature for five hours.
KeywordsB559 Complex Lithium Perchlorate Reaction Center Complex PSII Membrane Room Temperature Absorption Spectrum
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